Brake system

ABSTRACT

A brake system that includes a brake piston and a spindle. The brake piston includes a piston pocket defined in the brake piston. The piston pocket includes a threaded portion. The spindle includes a threaded portion. The threaded portion of the spindle is adapted to threadably engage the threaded portion of the piston pocket.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/550,043, filed Aug. 25, 2017 the entire contents of which is herebyincorporated by reference herein.

FIELD

These teachings relate to a brake system, and more particularly to abrake piston and a brake system.

BACKGROUND

A brake system typically includes a brake caliper configured to supportat least one brake piston. The brake piston is adapted to move at leastone brake pad into contact with a moving component to create a clampingforce. The clamping force may be used to slow, stop, or prevent movementof the moving component. In vehicular applications, the moving,component may be a brake rotor.

In some applications, the brake system may comprise a motor and a rotaryto linear stage mechanism. The rotary to linear stage mechanism may beadapted to convert torque from the motor into a linear force to move thebrake piston and the brake pad into contact with the moving component tocreate the damping force.

A typical rotary to linear stage mechanism comprises a spindle and anut. The spindle is in rotational communication with the motor, and thenut is threadably engaged with the spindle. To create the clampingforce, the spindle is rotated via the motor in an apply direction, whichcauses the nut to axially move in an apply direction until the nutcontacts a bottom pocket wall of the brake piston. After contact ismade, continued rotation of the spindle in the apply direction causesthe nut to push the brake piston in an apply direction until the brakepiston contacts a brake pad. Continued rotation of the spindle causesthe brake piston to push the brake pad into contact with the movingcomponent thus creating the clamping force.

While such systems may be satisfactory for creating clamping force,improvements may be desired.

For example, in some applications, it may be desirable to reduce thenumber of components in a brake system to reduce cost, complex, weight,and/or packaging space. It may also be desirable to reduce the number ofparts in such a brake system to simplify manufacturing and assembly ofthe system. Moreover, by reducing the number of components in a brakesystem, tolerance variations in the system may be reduced, which mayimprove overall system performance.

It may further be desirable to improve a brake system to improveresponse time in creating the clamping force. For example, in someapplications, a lag time may be realized between the time when the motorbegins rotating the spindle to when the nut takes up a gap definedbetween the nut and the bottom pocket wall of the brake piston and thenbegins to actually move the brake piston and the brake pad against themoving component to create the clamping force, in some brakingapplications, it may be desirable to reduce or eliminate this lag timeso that the brake piston and the brake pad can be moved when the motorbegins rotating the spindle.

Some examples of brake systems are found in U.S. Pat. Nos. 8,371,588;9,333,953; and 9,476,489, all of which are incorporated by referenceherein.

SUMMARY

These teachings provide a brake system and a brake piston. The brakepiston includes a piston body that extends along a longitudinal axis.The longitudinal axis may be the axis of the piston body and/or an axisof a caliper bore into which the piston body is received. A pistonpocket is formed or defined in the piston body. The piston pocketincludes a threaded portion that is adapted to directly, threadablyengage a threaded portion of a spindle rotation of the spindle causesthe brake piston to move axially along the longitudinal axis as soon asthe spindle is rotated.

Some known brake systems and/or brake pistons include a nut or othersliding member provided between the spindle and the brake piston. Duringuse of such a system that includes a nut, the spindle is rotated, whichcauses the nut to axially move along a length of the spindle until thenut contacts the brake piston. Further rotation of the spindle causesthe nut to eventually contact and then push the brake piston.Accordingly, a lag time may be realized between the time when thespindle is rotated and when the nut actually contacts the brake pistonand then beings to move the brake piston.

In contrast, and advantageously, the brake system according to theseteachings is free of a nut or similar sliding member provided betweenthe spindle and the brake piston. Instead, the spindle is directly,threadably connected to the brake piston. Rotation of the spindledirectly causes the brake piston to move. Accordingly, without such anut or sliding member, the number of parts in such the brake pistonand/or brake system is reduced, which advantageously results in reducedcost, complex, weight, and packaging space. Moreover, by eliminating thenut, the number of parts in such a bake piston and/or brake system arereduced, which advantageously results in simplified manufacturing andassembly. Furthermore, by eliminating the nut, an increase in responsetime can be achieved in creating the clamping force because as soon asthe spindle is rotated, the brake piston begins to axially move ratherthan waiting for a gap between the nut and bottom pocket wall to betaken up.

An outer surface of the brake piston according to the teachings hereincomprises one or more anti-rotation features. The one or moreanti-rotation features of the brake piston are configured to be engagedby one or more corresponding anti-rotation features defined in a caliperbore of a brake caliper. The anti-rotation features of the brake pistonand brake caliper cooperate to restrict or prevent the brake piston fromrotating about its longitudinal axis when the spindle is rotated;however, still allow for the brake piston to axially move axially alongits longitudinal axis in an apply and release direction.

The brake piston and/or system according to the teachings herein alsoincludes a piston seal with corresponding anti-rotation features thatare adapted to engage the anti-rotation feature of the brake piston. Thepiston seal is adapted to advantageously maintain parallelism of thebrake piston inside the caliper bore.

These teachings provide a brake system that includes a brake piston anda spindle. The brake piston includes a piston pocket defined in thebrake piston. The brake piston or piston pocket includes a threadedportion. The spindle also includes a threaded portion. The threadedportion of the spindle is adapted to threadably engage the threadedportion of the piston pocket.

These teachings also provide a brake system comprising a brake piston, aspindle, and a piston seal. The brake piston comprises an outer surfacehaving an anti-rotation feature. The brake piston comprises a pistonpocket. The piston pocket comprises a threaded portion. The spindlecomprises a threaded portion. The threaded portion of the spindle isadapted to threadably engage the threaded portion of the piston pocket.The spindle is in communication with a motor that is adapted to generatetorque, which causes the spindle to rotate. The piston seal surroundsthe outer surface of the brake piston. The piston seal comprises agenerally annular structure that comprises one or more anti-rotationfeatures. The anti-rotation feature of the piston seal is adapted toengage the anti-rotation feature of the brake piston. The brake pistonis adapted to be received in a caliper bore of a brake caliper. Thecaliper bore comprises an anti-rotation feature that is adapted toengage the anti-rotation feature of the brake piston so that the brakepiston is restricted from rotating within the caliper bore when thespindle is rotated by the motor.

These teachings also provide a brake system comprising a brake piston, aspindle, and a piston seal. The brake piston comprises a generallycircular outer surface having at least one flat surface. The brakepiston comprises piston pocket, the piston pocket comprises a threadedportion. The spindle comprises a threaded portion, that is adapted tothreadably engage the threaded portion of the piston pocket. The spindleis in communication with a motor that is adapted to rotate the spindle.The piston seal surrounds the outer surface of the brake piston. Thepiston seal comprises a generally annular structure that comprises atleast one flat surface disposed on an inner diameter thereof. The atleast one flat surface of the piston seal is adapted to engage the atleast one flat surface of the brake piston. The brake piston is adaptedto be received in a caliper bore of a brake caliper. The caliper borecomprises at least one flat surface that is adapted to engage the atleast one flat surface of the brake piston so that the brake piston isrestricted from rotating within the caliper bore when the spindle isrotated by the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a brake system.

FIG. 2 is a cross-sectional view of the brake system according to FIG.1.

FIG. 3 is an exploded, perspective view of a brake piston.

FIG. 4 is a close-up, cross-sectional view of the brake piston.

DETAILED DESCRIPTION

The brake assembly may be any system or assembly for creating a clampingforce. The brake system may function to create a clamping force to slow,stop, and/or maintain a moving component, such as a brake rotor or aroad wheel of a vehicle, in a stopped or parked position. The brakesystem may function to release the clamping force so that the movingcomponent, such as the brake rotor or the road wheel of the vehicle, canmove.

The brake system may be an opposing brake system (i.e., a fixed caliperbrake system) or a floating brake system (i.e., a floating caliper). Thebrake system may be a disc brake system. The brake system may be used asa service brake to slow, stop, and/or maintain a brake rotor, a roadwheel, or a vehicle, in a stopped position. The brake system may be usedas a parking brake to maintain a brake rotor, a road wheel, or avehicle, in a parked position.

Clamping force may be any force that, when coupled with a brake padcoefficient of friction, functions to decelerate, slow, stop, and/orprevent movement or rotation of a moving component. The clamping forcemay be created during a standard brake apply or application of theservice brake (i.e., a brake apply force) to slow, stop, or preventmovement of a moving component, a brake rotor, a road wheel, or vehicle.The clamping force may be created during a parking brake apply (i.e., aparking brake force) to prevent or restrict movement of a stopped orparked moving component, brake rotor, road wheel, or vehicle.

The brake system may comprise a brake caliper. The brake caliper mayfunction to support one or more the components of the brake system. Forexample, the brake caliper may comprise one or more supports forengaging and/or supporting one or more brake pads. The brake caliper maycomprise one or more caliper bores for supporting one or more brakepistons. For example, the brake caliper may comprise one or morefeatures for supporting an MGU or electric motor.

The brake caliper may move during a brake apply (i.e., a floatingcaliper), or the brake caliper may be fixed so that the brake caliperdoes not move during a brake apply (i.e., a fixed caliper). The brakecaliper may be connected or mounted to any non-rotating or moving partof a machine, structure, or vehicle, like a knuckle or a spider of avehicle, which may be the casting that a disc brake system is mountedto.

The brake caliper may comprise one or more caliper bores. A caliper boremay be a hollow region, pocket, bore, or through-bore defined in thebrake caliper that is configured or adapted to receive and support acorresponding brake piston. A brake caliper may have one caliper bore. Abrake caliper may have more than one caliper bores. All of the caliperbores may be located on one side of the brake caliper or brake rotor.Some of the caliper bores may be located on one side of the brakecaliper or brake rotor, and some of the caliper bores may be located onan opposite side of the brake rotor or brake rotor. One or more of thecaliper bores can be located on only one side of the moving component orbrake rotor (i.e., either the inboard side or the outboard side), or oneor more caliper bores can be located on both sides of the movingcomponent or brake rotor (i.e., both of the inboard side and theoutboard side).

Each caliper bore may comprise one or more anti-rotation features. Theone or more anti-rotation features of the caliper bore may function torestrict or prevent the brake piston from rotating about a longitudinalaxis of the brake piston or caliper bore. The one or more anti-rotationfeatures of the caliper bore may function to restrict or prevent thebrake piston from rotating about the longitudinal axis of the brakepiston or caliper bore when the spindle is rotated. The one or moreanti-rotation features of the caliper bore may cooperate with and/orengage one or more corresponding anti-rotation features defined on Outersurface of the brake piston; may cooperate with and/or engage the pistonseal; may cooperate with and/or engage any other portion of the brakepiston, to restrict or prevent the brake piston from rotating. The oneor more anti-rotation features of the caliper bore may cooperate withand or engage one or more corresponding anti-rotation features definedon outer surface of the brake piston to maintain the brake piston in aparticular position for example, to maintain parallelism or squarenessof the brake piston inside the caliper bore. The one or moreanti-rotation features of the caliper bore may cooperate with and/orengage the piston seal, which may cooperate with and/or engage one ormore corresponding anti-rotation features defined on outer surface ofthe brake piston to maintain parallelism or squareness of the brakepiston inside the caliper bore. The one or more anti-rotation featuresof the caliper bore may cooperate with and/or engage the piston seal,which may cooperate with and/or engage one or more correspondinganti-rotation features defined on. outer surface of the brake piston tomaintain the longitudinal axis of the brake piston in a co-linearrelationship with the longitudinal axis of the caliper bore.

The one or more anti-rotation features of the caliper bore may belocated on one or on more portions, sections, surfaces, or features of acaliper bore. For example, the one or more anti-rotation features of thecaliper bore may be located along a single plane that is generallyperpendicular to a longitudinal axis of the caliper bore. The one ormore anti-rotation features of the caliper bore may be located along anentire length of depth of the caliper bore, or only along a selectedportion thereof.

The one or more anti-rotation features of the caliper bore may comprisesubstantially flat sections or linear surfaces relative to the circulardiameter of the caliper bore. The flat sections or linear surfaces maybe a tangent line, plane, or surface to the circular outer diameter ofthe caliper bore. The one or more anti-rotation features of the caliperbore may have other geometry, such as, for example, a toothed or notchedgeometry. The one or more anti-rotation features may include areas withincreased coefficient of friction relative to the rest of the circularouter surface or diameter of the caliper bore. The one or moreanti-rotation features may include bumps, nubs, notches, grooves,texture, or a combination thereof that function to engage or contactother corresponding anti-rotation features to prevent the brake pistonfrom rotating, while along the brake piston to axially move along alongitudinal axis.

The one or more anti-rotation features of the caliper bore may besubstantially the same as or compliment the one or more anti-rotationfeatures of the brake piston and/or the one or more anti-rotationfeatures of the piston seal.

The brake system may comprise one or more brake pistons. The one or morebrake pistons may function to move a brake pad, or a corresponding endof brake pad towards a moving component or brake rotor to create theclamping force. The one or more brake pistons may function to move awayfrom a brake pad, or a corresponding end of brake pad so that the brakepad or the corresponding end of a brake mad moves away from a movingcomponent or brake rotor to release the clamping force.

The one or more brake pistons can be mechanically moved, for example, bymoving or rotating a corresponding spindle. The one or more brakepistons may be moved with the torque generated by the motor, which isthen transferred or supplied to the brake piston via a correspondingspindle. Because the spindle is threadably engaged directly to the brakepiston, movement of the spindle results in direct and generallyimmediate movement of the brake piston, either towards or away from thebrake pad, depending on the direction of rotation of the spindle (e.g.,clockwise vs. counterclockwise/apply vs. release direction). The one ormore brake pistons according to the teachings herein are free from beingmoved by pressurizing a fluid, like hydraulic fluid. Thus, to create aclamping force whether during application of the service brake orapplication of the parking brake, the brake piston is moved by movingthe spindle. However, a fluid may be supplied to the one or more brakepistons to lubricate the components thereof, for example, the threadedportions of the brake piston and spindle.

Each brake piston comprises a piston pocket. The piston pocket may be acup, recess, or a hollow portion formed into an end of a brake piston.The piston pocket may be a through hole that extends from one end of thebrake piston through to the other end of the brake piston. The pistonpocket may be adapted to directly receive and engage at least a portionof a corresponding spindle.

The piston pocket may comprise a threaded portion. The threaded portionof the piston pocket may function to threadably engage the threadedportion on the spindle. The threaded portion may be integrally formedinto the piston pocket. Alternatively, the threaded portion may be partof a sleeve that is press-fit and/or otherwise mechanically locked orbonded to the piston pocket so that the threaded portion and the brakepiston are generally a single, monolithic structure.

The one or more anti-rotation features of the brake piston may functionto restrict or prevent the brake piston from rotating about alongitudinal axis of the brake piston and/or caliper bore. The one ormore anti-rotation features of the brake piston may function to restrictor prevent the brake piston from rotating about the longitudinal axis ofthe brake piston and/or caliper bore when the spindle is rotated. Theone or more anti-rotation features of the brake piston may cooperatewith and/or engage one or more corresponding anti-rotation featuresdefined on the inner surface of the caliper bore to restrict or preventthe brake piston from rotating but allow for the brake piston to moveaxially along a longitudinal axis of the caliper bore or brake piston.

The one or more anti-rotation features of the brake piston may cooperatewith and/or engage one or more corresponding anti-rotation featuresdefined in the caliper bore to maintain the brake piston in a particularposition—for example, to maintain parallelism or squareness of the brakepiston inside the caliper bore. The one or more anti-rotation featuresof the brake piston may cooperate with and/or engage the one or morecorresponding anti-rotation features of the piston seal, which maycooperate and/or engage the caliper bore to maintain parallelism orsquareness of the brake piston inside the caliper bore.

The one or more anti-rotation features of the brake piston may belocated on one or on more portions, sections, surfaces, or features of abrake piston. For example, the one or more anti-rotation features of thebrake piston may be located along a single plane that is generallyperpendicular to a longitudinal axis of the brake piston. The one ormore anti-rotation features of the brake piston may be located along anentire length of the brake piston, or only along a selected portionthereof.

The one or more anti-rotation features of the brake piston may besubstantially flat or linear surfaces. The one or more anti-rotationfeatures of the brake pistons may be flat or tangent surfaces relativeto the rest of the circular outer circumference of the brake piston. Thefiat sections or linear surfaces of the brake piston may be a tangentline, plane, or surface to the circular outer diameter of the caliperbore. The one or more anti-rotation features of the brake piston mayhave other geometry, such as, for example, a toothed or notchedgeometry. The one or more anti-rotation features of the brake piston mayhave other geometry, such as, for example, a toothed or notchedgeometry. The one or more anti-rotation features may include areas withincreased coefficient of friction relative to the rest of the outersurface of the brake piston. The one or more anti-rotation features mayinclude bumps, nubs, notches, grooves, texture, or a combination thereofthat function to engage or contact other corresponding anti-rotationfeatures to prevent the brake piston from rotating, while along thebrake piston to axially move along a longitudinal axis. The one or moreanti-rotation features of the brake piston may be substantially the sameas or match the one or more anti-rotation features of the caliper boreand/or piston seal,

The one or more anti-rotation features of the brake piston and/orcaliper bore may be of the ones disclosed in Applicant's U.S. patentapplication Ser. No. 15/797,172 filed on Oct. 30, 2017, the disclosureof which is hereby incorporated by reference herein for all purposes.For example, referring to Applicant's U.S. patent application Ser. No.15/797,172, the anti-rotation features may be one or more of the clips132, 134, O-ring 234, and the corresponding groove 124 or 224 defined inthe piston pocket.

The one or more anti-rotation features of the brake piston, the pistonseal, the caliper bore, or a combination thereof may function torestrict or prevent the brake piston from rotating about a longitudinalaxis of the brake piston and/or caliper bore during a condition when thespindle is rotated but before the brake piston contacts the brake pad.After the brake piston contacts the brake pad, the one or moreanti-rotation features of the brake piston, the piston seal, the caliperbore, or a combination thereof may or may not continue to restrict orprevent the brake piston from rotating about its longitudinal axis whenthe spindle is rotated.

The face or forward surface of the brake piston may contain a featurethat is configured to contact and/or engage a corresponding feature onthe pressure plate of the corresponding brake pad to restrict or preventthe brake piston from rotating about its longitudinal axis while thespindle is rotated. The one or more features may be, for example, atextured or hatched portion, one or more bumps, nubs, grooves,projections, or a combination thereof. Therefore, the one or moreanti-rotation features of the brake piston, the piston seal, the caliperbore, or a combination thereof need only to restrict or prevent thebrake piston from rotating up until a time the brake piston contacts thebrake rotor. After that, the one or more anti-rotation features of thebrake piston, the piston seal, the caliper bore, or a combinationthereof may continue to restrict or prevent the brake piston fromrotating but do not need to because of the one or more features betweenthe face of the brake piston and the pressure plate of the brake padthat function to restrict or prevent the brake piston from rotating whenthe spindle is rotated.

The brake system may comprise one or more rotary to linear stagemechanisms. A rotary to linear stage mechanism may function to transferor convert torque from the motor or MGU into a linear or axial force toaxially move a brake piston.

The rotary to linear stage mechanism may be a high-efficiency device. Anexample of a high-efficiency device is a ball screw. The high efficiencydevice is a device that is more efficient than a low efficiency device.Efficiency may refer to how well, or how “efficiently” the deviceconverts or transfers torque from a motor or MGU into a linear load oroutput force. Depending on one or more considerations, such as leadangle and coefficient of fiction, the one or more high efficiencydevices may have an efficiency on the order of approximately 60% ormore, approximately 70% or more, approximately 80% or more,approximately 85% or more, approximately 90% or more, approximately 95%or more, 97% or more, or even 99% or more. The rotary to linear stagemechanism may be a low-efficiency device. An example of a low-efficiencydevice is a lead screw.

Each of the one or more rotary to linear stage mechanisms comprise thebrake piston disclosed herein and a corresponding spindle. The rotary tolinear stage mechanism may be defined at or as the threaded portion ofthe brake piston and the corresponding threaded portion of the spindle.The rotary to linear stage mechanism according to these teachings isfree of a nut that is threaded onto the spindle instead, the brakepiston directly threadably engages the spindle. One or more rollers orball bearings or other load transferring members may be located betweenthe brake piston and the spindle. For example, ball bearings may belocated in a track defined by the threaded portion of the spindle andthe corresponding threaded portion of the brake piston.

Because it is a high-efficiency mechanism, a sufficient brake or otherlow efficiency mechanism may be required to maintain the clamping forceafter it is created in order to prevent the high-efficiency system fromback driving. That is, after the clamping force is created, a sufficientbrake is required in order to prevent the spindle from rotating withinthe brake piston in an opposing release direction due to the opposingreaction force of the clamping force acting on the brake piston.

The rotary to linear stage mechanism or the high efficiency deviceaccording to these teachings may be a ball screw or a roller screw forexample. Exemplary ball screws may utilize ball bearings as loadtransfer elements between the threaded portion of the spindle and thethreaded portion of the brake piston. During rotation of the spindle,the ball bearings may circulate along races or grooves between thethreaded portions of the spindle and brake piston. A roller screw orplanetary screw may be similar to a ball screw except that roller screwsuse rollers as the load transfer elements between spindle and the brakepiston. The load is distributed over a large number of ball bearings orrollers, via roller threads, respectively, so that each ball bearing orroller, when subjected to force, may roll, and therefore, friction isreduced, which may equate to high efficiency. Accordingly, less force ortorque may be required to move the spindle and piston in an applydirection, a release direction, or both. However, the one or more rotaryto linear stage mechanisms may be a low-efficiency device.

The brake system may comprise one or more spindles. A spindle mayinclude threaded portion and an input portion. The threaded portion maythreadably engage the threaded portion of a brake piton. The inputportion may engage or be engaged by a motor or MGU or other transfergear to rotate the spindle The spindle may be rotated about an axis thatis the same as or collinear with a longitudinal axis of the brake pistonand/or caliper bore. The spindle may be rotated in an apply direction todevelop or generate clamping force and in a release direction to releasethe clamping force. The apply direction may be clockwise, and therelease direction may be counter-clockwise, or vice versa.

The brake system and/or the brake piston and/or the rotary to linearstage mechanism may be free of a nut. This means that there is no nut orother sliding or pushing member provided between the spindle and brakepiston. This means the brake system and/or the brake piston and/or therotary to linear stage mechanism is free of a nut that threadablyengages the threaded portion of the spindle. Instead, the spindle isconfigured to directly contact and engage the brake piston. Morespecifically, the threaded portion of the spindle is configured todirectly threadably engage the threaded portion of the brake piston orpiston pocket. The spindle is thus configured to directly move or pushthe brake piston against the brake pad and then move or push the brakepad against the brake rotor to create and/or maintain the clamping forcerequired to slow, stop, or prevent movement of the brake rotor or roadwheel of a vehicle. Conversely, in systems that comprise a nut thatthreadably engages the spindle, the spindle is configured to move thenut, and the nut is configured to contact and then move or push thebrake piston and then the brake pad against the brake rotor to create orgenerate clamping force. By having a system that is free of a nut, a lagtime between when the spindle is rotated to when the brake piston isactually moved is reduced or eliminated. This is because the brakesystem no longer has to wait for the gap between the nut and the bottomof the piston pocket to be taken up (i.e., no longer has to wait for thenut to be moved into contact with the brake piston) before the brakepiston is actually moved or pushed with the nut when the spindle isrotated. Instead, when the spindle is rotated, the brake piston is movedaxially along the longitudinal axis.

The brake system and/or the brake piston may comprise one or more pistonseals. The piston seal may function to restrict or prevent the brakepiston from rotating in the caliper bore about its longitudinal axiswhen the spindle is rotated. The piston seal may function to maintain acentered position of the brake piston relative to the caliper bore. Thepiston seal may function to maintain parallelism and/or squareness ofthe brake piston within the caliper bore, The piston seal may functionto maintain a longitudinal axis of the brake piston collinear with orthe same as the longitudinal axis of the caliper bore.

The piston seal may surround an outer surface of the brake piston. Thepiston seal may be located in a groove, notch, or cutout defined in thecaliper bore. The piston seal may be sandwiched between the brake pistonand the caliper bore. The piston seal may have a generally circular,annular shape, and may be formed of a rubber or similar playablematerial.

An inner diameter or surface of the annular piston seal may comprise oneor more anti-rotation features. The one or more anti-rotation featuresof the piston seal may cooperate with and/or engage one or morecorresponding anti-rotation features defined on the outer surface of thebrake piston to maintain the brake piston in a particular position—forexample, to maintain parallelism or squareness of the brake pistoninside the caliper bore.

The one or more anti-rotation features of the piston seal may be locatedon one or on more portions, sections, surfaces, or features of a pistonseal. The one or more anti-rotation features of the piston seal may besubstantially flat or linear sections or surfaces. The one or moreanti-rotation features of the piston seal may be flat or tangentsurfaces relative to the rest of the circular or annular piston seal.The one or more anti-rotation features of the piston seal may have othergeometry, such as, for example, a toothed or notched geometry. The oneor more anti-rotation features of the piston seal may have othergeometry, such as, for example, a toothed or notched geometry. The oneor more anti-rotation features may include areas with increasedcoefficient of friction. The one or more anti-rotation features mayinclude bumps, nubs, notches, grooves, texture, or a combination thereofthat function to engage or contact other corresponding anti-rotationfeatures to prevent the brake piston from rotation, while along, thebrake piston to axially move along a longitudinal axis. The one or moreanti-rotation features of the piston seal may be substantially the sameas or match the one or more anti-rotation features of the caliper boreand/or brake piston.

The brake system may comprise one or more brake pads. Each brake padincludes a friction material and a pressure plate. The one or more brakepads may be supported on the brake caliper so that the friction materialfaces a side of the moveable member or brake rotor. The pressure platemay oppose the friction surface. One or more brake pistons, or one ormore brake caliper fingers, may contact the pressure plate of acorresponding brake pad. For example, in some cases, one or more brakepistons may be in contact with the pressure plate of an inboard brakepad, and one or more brake caliper fingers may be in contact with thepressure plate of an outboard brake pad. In some cases, one or morebrake pistons may be in contact with the pressure place of an inboardbrake pad, and one or more brake pistons may be in contact with thepressure place of an outboard brake piston. During a brake apply, orwhile applying the parking brake, the one or more brake pistons and/orthe one or more fingers can move all or an end of a corresponding brakepad so that the corresponding friction material engages a correspondingside of the moveable member or brake rotor to create the clamping force.

The brake system may cooperate with a moveable member to create theclamping force. The moveable member may be any moveable part. Invehicular applications, the moveable member may be a brake rotor. Thebrake rotor is the rotating pan the brake assembly, against which one ormore of the brake pads are moved or applied to create the clampingforce.

The brake system may include a motor gear unit (MGU). The MGU mayfunction to create or generate a force or torque, and then transfer theforce or torque to one or more components of the brake system to create,increase, decrease, and/or release the clamp force. The MGU may functionto generate torque sufficient to move the one or more rotary to linearstage mechanisms, the one or more brake pistons, the one or more brakepads, or a combination thereof toward the brake rotor to create dragwith the one or more brake pads against the brake rotor, which acts todevelop the clamping force. The MGU may function to generate torque thatis sufficient to move the one or more rotary to linear stage mechanisms,the one or more brake pistons, or both away from the one or more brakepads so that the brake pads move away from the brake rotor so that thedrag is reduced or eliminated to release the clamping force.

The MGU may be any device or combination of devices that may perform oneor more of the aforementioned functions. For example, the MGU mayinclude a motor that generates torque. For example, the motor may be aDC motor, a brushless motor, a series-wound motor, a shunt wound motor,a compound wound motor, a separately exited motor, a servomotor, astepping motor, or a permanent magnet motor. The MGU may include one ormore gears or gear trains that may function to transfer, increase,and/or decrease the torque output of the motor. The MGU may or may notinclude a lock or brake to prevent back driving of the one or morerotary to linear stage mechanisms after the clamp force is created andafter the MGU is turned. OFF or disconnected. For example, the MGU mayinclude a wrap spring, solenoid, or other mechanism to maintain theclamp force after the MGU is turned OFF or is disconnected.

FIG. 1 illustrates a brake system 10. The brake system 10 comprises acaliper body 12. The caliper body 12 comprises a brake piston supportingsection 14, a bridge 16, and fingers 18. The brake system 1.0 comprisesa motor gear unit (MGU), which is schematically illustrated at 20.

FIG. 2 illustrates the brake system 10. The caliper body 12 is adaptedto support an inboard brake pad, which is schematically illustrated at22 and is located adjacent the brake piston supporting section 14. Thecaliper body 12 is adapted to support an outboard brake pad, which isschematically illustrated at 24 and is located adjacent the fingers 18.A brake rotor, illustrated schematically at 26, is supported in betweenthe inboard and outboard brake pads 22, 24, and comprises an inboardbraking surface 28 facing the inboard brake pad 22, and an outboardbraking surface 30 facing the outboard brake pad 24.

With continued reference to FIG. 2, at the brake piston supportingsection 14, the brake system 10 comprises a pair of caliper bores 32 a,32 b. It is understood, however, that the brake system 10 can compriseany number of caliper bores 32 a, 32 b, including one caliper bore, oreven three or more caliper bores. In addition, or alternatively, it isalso understood that the brake system 10 can comprise any number ofcaliper bores located at the other side of the brake rotor 26. In otherwords, while the brake system 10 illustrated in FIGS. 1 and 2 is asliding type of brake system 10, the brake system may instead be anopposed piston brake system. In other words, while the brake system 10illustrated in FIGS. 1 and 2 shows only caliper bores at the inboardside, the brake system 10 may have caliper bores only at the outboardside.

The brake system 10 comprises a brake piston 34 a, 34 b supported ineach caliper bore 32 a, 32 b. The brake system 10 comprises a controller36 that may be in communication with the MGU 20.

FIG. 3 illustrates the brake piston 34, which may be one or both of thebrake pistons 34 a, 34 b illustrated in FIG. 2. The brake piston 34comprises a piston body 38, which extends along a longitudinal axis 40;a spindle 42; a piston seal 44; a thrust bearing assembly 46; a spindleO-ring 48; and a retaining clip 50.

An outer surface 52 of the piston body 38 comprises a pair ofanti-rotation features 54 that generally oppose one another. Statedanother way, the anti-rotation features 54 are located on opposing sidesof the piston body 38. However, in some configurations, the piston body38 may include only one anti-rotation feature 54. However, in someconfigurations, the piston body 38 may include more than twoanti-rotation features 54. In configurations where the piston body 38includes two or more anti-rotation features 54, the anti-rotationfeatures may be equally spaced around the piston body 38 or unequallyspaced around the piston body 38.

The outer surface 52 of the piston body 38 is generally circular, andthe anti-rotation features 54 are generally fiat sections relative tothe generally circular outer surface 52. The anti-rotation features 54of the brake piston 38 are adapted to engage or be engaged bycorresponding anti-rotation features 56 (FIG. 4) defined in the caliperbore 32 of the caliper body 12.

The caliper bore 32 is also generally circular, and the anti-rotationfeatures 56 of the caliper bore 32 are generally flat sections relativeto the generally circular caliper bore 32. The anti-rotation features54, 56 cooperate to restrict or prevent the brake piston 34 fromrotating inside the caliper bore 32 about the axis 40. For example, theanti-rotation features 54, 56 cooperate to restrict or prevent the brakepiston 34 from rotating inside the caliper bore 32 about the axis 40when the spindle 42 is rotated by the MGU 20.

The piston body 38 comprises a piston pocket 58. The piston pocket 58 isa bore or pocket or cup or absence of material defined in the pistonbody 38. The piston pocket 58 comprises a threaded portion 60 that isdefined or formed directly in or on the inside annular wall or side walldefining the piston pocket 58. Alternatively, the threaded portion 60may be a sleeve or insert that is tit into the piston pocket 58. Thethreaded portion 50 is adapted to directly, threadably engage acorresponding threaded portion 62 of the spindle 42.

The spindle 42 comprises a threaded portion 62 that is configured todirectly, threadably engage the threaded portion 60 of the piston body38. One or more ball bearings or rollers 61 may be located in grooves,channels, or races defined by the corresponding threaded portions 60, 62so that the spindle 42 and the piston body 38 function like ahigh-efficiency rotary to linear motion mechanism, for example a ballscrew. However, in some configurations, the system may be free of anyball bearings or rollers located in grooves, channels, or races definedby the corresponding threaded portions 60, 62. In such configurations,the spindle 42 and the piston body 38 may function like a low-efficiencyrotary to linear motion mechanism, for example a lead screw.

The spindle comprises an input portion 64. The input portion 64 of thespindle 42 is adapted to directly or indirectly (via one or more gears)engage the MGU 20 (FIG. 2) so that when the MGU 20 generates torque, thetorque is transmitted to the input portion 64 of the spindle 42 so thatthe spindle 42 is rotated about the longitudinal axis 40. As will bediscussed further below, rotation of the spindle 42 about thelongitudinal axis 40 causes the brake piston 32 to move axially alongthe longitudinal axis 40.

The piston seal 44 is a generally annular structure that is adapted totit around and surround the outer surface 52 of the piston body 38. Thepiston seal 44 comprises anti-rotation features 66 disposed around aninner diameter thereof. The ant-rotation features 66 generallycorrespond to and are adapted to engage the corresponding ant-rotationfeatures 54 located on the outer surface 52 of the piston body 38. Theanti-rotation features 66 generally oppose one another. Stated anotherway, the anti-rotation features 66 are located on opposite sides of thepiston seal 44. The anti-rotation features 66 are generally flatsections relative to the generally annular structure of the piston seal44.

The thrust bearing assembly 46 comprises a thrust bearing 68 that issupported in a cage 70. The cage 70 comprises a hanger 72 for engagingthe caliper body 12 and securing the thrust bearing assembly 46 to thecaliper body 12 to prevent the cage 70 from rotating or otherwisemoving. The thrust bearing 68 comprises an input portion 74 throughwhich the input portion 64 of the spindle 42 is received. The spindleO-ring 48 comprises an input portion 76 that is adapted to receive theinput portion 64 of the spindle 42. The retaining clip 50 is adapted tosurround at least a portion of the input portion 64 of the spindle 42and restrict or prevent the spindle 42 from axially moving along thelongitudinal axis 40 when the brake assembly 10 is assembled. A pistonboot 78 is adapted to surround the piston body 38.

FIG. 4 is a cross-sectional view of the brake piston 34 that issupported in the caliper bore 32 of the caliper body 12. The piston seal44 surrounds the outer surface 52 of the piston body 38 is supported ina recess 80 defined in the caliper body 12. The piston boot 78 isadapted to surround the piston body 38. The threaded portion 62 of thespindle 42 is adapted to threadably engage the threaded portion 60 ofthe piston pocket 58 so that when the spindle 42 is rotated by torqueoutput from the MGU 20 (FIGS. 1 and 2), the brake piston 34 movesaxially along the axis 40 in an apply or release direction towards oraway from the inboard brake pad. One or more ball bearings or rollers 61may be located in grooves, channels, or races defined by thecorresponding threaded portions 60, 62 so that the spindle 42 and thepiston body 38 function like a high-efficiency rotary to linear motionmechanism, for example a ball screw. However, in some configurations,the system may be free of any ball bearings or rollers located ingrooves, channels, or races defined by the corresponding threadedportions 60, 62 In such configurations, the spindle 42 and the pistonbody 38 may function like a low-efficiency rotary to linear motionmechanism, for example a lead screw.

The outer surface 52 of the piston body 38 comprises anti-rotationfeatures 54 that are engaged by corresponding anti-rotation features 56defined in the caliper bore 32 of the caliper body 12. The anti-rotationfeatures 54, 56 cooperate to restrict or prevent the brake piston 34from rotating about the axis 40 when the spindle 42 is rotated.

The retaining clip 50 is positioned at an outer surface 82 of thecaliper body 12 and is adapted to restrain the spindle 42 from movingaxially along the longitudinal axis 40. The thrust bearing assembly 46is sandwiched between an inside surface 84 of the caliper body 12 and aflange 86 of the spindle 42.

A method of assembling the brake system 10 and/or the brake piston 34will now be described with reference to the foregoing figures. It isunderstood that the following steps can be performed in virtually anyorder. Moreover, one or more of the following steps can be combined;omitted or eliminated; repeated; or separated into additional,individual or discrete steps. In the interest of brevity, the followingsteps are described for assembling one brake piston 34 and brake system10. A brake system 10 that includes more than one brake piston 34 can beassembled in virtually the same manner by repeating one or more of thesesteps,

The method of assembling the brake system 10 and/or the brake piston 34(hereafter “method of assembling”) includes a step of inserting thespindle 42 into the piston pocket 58 and threadably engaging thethreaded portion 62 of the spindle 42 with the threaded portion 60 ofthe brake piston 34 or piston body 38. The method of assembling includesa step of attaching or sliding the generally annular piston seal 44 ontoor over the outer surface 52 of the brake piston 34 or piston body 38such that the anti-rotation feature 66 or fiat sections of the pistonseal 44 engage or contact the anti-rotation feature 54 or flat sectionsof the brake piston 34 or piston body 38. The method of assemblingincludes a step of assembling or sliding the input portion 74 of thethrust bearing assembly 46 onto the input portion 64 of the spindle 42.The method of assembling includes a step of assembling or sliding theinput portion 76 of the O-ring onto the input portion 64 of the spindle42 until the O-ring contacts or touches the thrust bearing cage 70 orthrust bearing assembly 46. The method of assembling includes a step ofassembling or sliding the piston boot 78 onto an outer surface 52 of thebrake piston 34 or piston body 38. The method of assembling includes astep of inserting the brake piston 34 into the caliper bore 32 of acaliper body 12 such that the thrust bearing assembly 46 is sandwichedbetween an inner surface 84 of the caliper body 12 and the flange 86 ofthe spindle 42. The method of assembling includes a step of attachingthe clip 50 to the input portion of the spindle 42 as it projectsoutside of the caliper body 12 so that the clip 50 prevents axialmovement of the spindle 42 relative to the axis 40.

Operation of the brake system 10 to create the damping force will now bedescribed in the following steps with reference to the foregoingfigures. It is understood that the following method steps can beperformed in virtually any order. Moreover, one or more of the followingmethod steps can be combined; omitted or eliminated; repeated; orseparated into additional individual steps.

Creating damping force includes a step of activating the brake system10. This step may be performed manually by depressing a brake pedal orpushing or activating a button or lever. This step may be performedautomatically, for example, when a vehicle is put into a “Park” gear oran engine or motor is turned OFF. Creating clamping force includes astep of transmitting a signal from the controller 36 to the MGU 20 afterthe system 10 is activated. Creating clamping force includes a step oftransmitting or supplying, the MGU 20 or motor with a current, avoltage, power, a signal, or a combination thereof to begin generatingtorque. The torque generated by the motor or MGU 20 may be transmittedto or through one or more gears or a gear stage to increase or decreasethe torque output. Creating clamping force includes a step of supplyingthe torque to the input portion 64 of the spindle 42 so that the spindle42 is rotated about the axis 40 in an apply direction. The applydirection may be clockwise or counter-clockwise. Rotating of the spindle42 in the apply direction causes the piston body 38 to move axiallyalong the axis 40 towards the corresponding brake pad 22, 24. That is, abrake piston 32 located at the inboard side of the caliper body 12 willbe moved towards the inboard brake pad 22 and a brake piston 32 locatedat the outboard side of the caliper body 12 will be moved towards theoutboard brake piston 24. During this axial movement of the brake piston32 along axis 40, the brake piston 34 or piston body 36 is restricted orprevented from rotating about the axis 40 by way of the anti-rotationfeatures 54 or flat sections of the piston body 38 engaging thecorresponding anti-rotation features 56 or that sections of the caliperbore 32. Also, the piston seal 44 and its corresponding anti-rotationfeatures 66 or flat sections engaging the corresponding anti-rotationfeatures 54 or flat sections of the caliper body 38 and the innerportion of the caliper bore 58 restricts or prevents rotation of thecaliper body 38 or brake piston 34, while also maintaining parallelismof the piston body 38 within the caliper bore 32.

The brake piston 34 or piston body 38 is moved until the front end 88 ofthe brake piston 34 contacts the pressure plate of the correspondingbrake pad 22, 24. After contact is made, continued rotation of thespindle 42 and thus movement of the brake piston 34 or piston body 38 inthe apply direction causes the corresponding brake pad 22, 24 to bemoved in the apply direction until the corresponding friction materialof the brake pad 22, 24 is pressed into contact with the brake rotor 26or other moveable member. The brake pad 22, 24 is pressed into contactwith the brake rotor 26 until a sufficient clamping force is achieved.

Operation of the brake system 10 to release the clamping force will nowbe described in the following steps with reference to the foregoingfigures. Again, it is understood that the following steps can beperformed in virtually any order. Moreover, one or more of the followingsteps can be combined; omitted or eliminated; or separated intoadditional individual steps.

Releasing clamping force includes a step of activating the brake system10. This step may be performed manually by releasing a brake pedal orpushing or activating a button or lever. This step may be performedautomatically, for example, when a vehicle is put into a “Drive” gear oran engine or motor is turned ON. Releasing clamping force includes astep of transmitting a signal from the controller 36 to the MGU 20 afterthe system 10 is activated Releasing clamping force includes a step oftransmitting or supplying the MGU 20 or motor with a current, a voltage,power, a signal, or a combination thereof to begin generating torque.The torque generated by the motor or MGU 20 may be transmitted to orthrough one or more gears or a gear reduction stage to increase ordecrease the torque output. Releasing clamping force includes a step ofsupplying the torque to the input portion 64 of the spindle 42 so thatthe spindle 42 is rotated about the axis 40 in a release direction. Therelease direction is opposite the direction that the spindle 42 isrotated during creation of the clamping force. The release direction maybe clockwise or counter-clockwise. Rotating of the spindle 42 in therelease direction causes the piston body 38 to move axially along theaxis 40 away from the corresponding brake pad 22, 24. That is, a brakepiston 32 located at the inboard side of the caliper body 12 will bemoved away from the inboard brake pad 22 and a brake piston 32 locatedat the outboard side of the caliper body 12 will be moved away from theoutboard brake piston 24. During this axial movement of the brake piston32 along axis 40, the brake piston 34 or piston body 38 is restricted orprevented from rotating about the axis 40 by way of the anti-rotationfeatures 54 or flat sections of the piston body 38 engaging thecorresponding anti-rotation features 56 or flat sections of the caliperbore 32. Also, the piston seal 44 and its corresponding anti-rotationfeatures 66 or flat sections engaging the corresponding anti-rotationfeatures 54 or flat sections of the caliper body 38 and the innerportion of the caliper bore 58 restricts or prevents rotation of thecaliper body 38 or brake piston 34, while also maintaining parallelismof the piston body 38 within the caliper bore 32.

The brake piston 34 or piston body 38 is moved until the front end 88 ofthe brake piston 34 disengages or is no longer in contact with thepressure plate of the corresponding brake pad 22, 24. The brake pads 22,24 may then move away from a corresponding side of the brake rotor 26.

The explanations and illustrations presented herein are intended toacquaint others skilled in the art with the invention, its principles,and its practical application. The above description is intended to beillustrative and not restrictive. Those skilled in the art may adapt andapply the invention in its numerous forms, as may be best suited to therequirements of a particular use.

Accordingly, the specific embodiments of the present invention as setforth are not intended as being exhaustive or limiting of the teachings.The scope of the teachings should, therefore, be determined not withreference to this description, but should instead be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled. The omission in thefollowing claims of any aspect of subject matter that is disclosedherein is not a disclaimer of such subject matter, nor should it beregarded that the inventors did not consider such subject matter to bepart of the disclosed inventive subject matter.

Plural elements or steps can be provided by a single integrated elementor step. Alternatively, single element or step might be divided intoseparate plural elements or steps. The disclosure of “a” or “one” todescribe an element or step is not intended to foreclose additionalelements or steps. By use of the term. “may” herein, it is intended thatany described attributes that “may” be included are optional.

The disclosures of all articles and references, including patentapplications and publications, are incorporated by reference for allpurposes. Other combinations are also possible as will be gleaned fromthe following claims, which are also hereby incorporated by referenceinto this written description.

1) A brake system comprising: a brake piston comprising a piston pocket,the piston pocket comprises a threaded portion defined in a side wallthereof; and a spindle comprising a threaded portion; wherein thethreaded portion of the spindle is adapted to threadably engage thethreaded portion of the piston pocket. 2) The brake system according toclaim 1, wherein the brake piston comprises an outer surface comprisingan anti-rotation feature; wherein the brake piston is adapted to besupported in a caliper bore of a brake caliper; and wherein the caliperbore is adapted to engage the anti-rotation feature of the brake pistonto restrict or prevent the brake piston from rotating within the caliperbore. 3) The brake caliper according to claim 2, wherein the outersurface of the brake piston is generally circular, and the anti-rotationfeature of the brake piston is a generally flat section. 4) The brakecaliper according to claim 3, wherein the brake piston comprises twoanti-rotation features. 5) The brake caliper according to claim 4,wherein the two anti-rotation features of the brake piston generallyoppose each other. 6) The brake system according to claim 1, wherein thebrake system is free of a nut provided between the spindle and the brakepiston. 7) The brake system according to claim 2, wherein the brakesystem comprises a piston seal, the piston seal comprises a generallyannular structure that includes an anti-rotation feature disposed on aninner diameter thereof that corresponds to the anti-rotation feature ofthe brake piston. 8) The brake system according to claim 7, wherein thepiston seal comprises two anti-rotation features and the brake pistoncomprises two anti-rotation features. 9) The brake system according toclaim 1, wherein one or more ball bearings are provided in groovesdefined by the threaded portion of the of the piston pocket and thethreaded portion of the spindle. 10) The brake system according to claim1, wherein the brake caliper comprises more than one caliper bore, andeach of the more than one caliper bore is adapted to support one of thebrake pistons. 11) The brake system according to claim 10, wherein allof the caliper bores are located on one side of the brake caliper. 12)The brake system according to claim 10, wherein some of the caliperbores are located on one side of the brake caliper, and some of thecaliper bores are located on an opposite side of the brake caliper. 13)A method of assembling the brake system according to claim 1, whereinthe method comprises a step of: inserting the spindle into the pistonpocket and directly threadably engaging the threaded portion of thespindle with the threaded portion of the brake piston. 14) The methodaccording to claim 13, wherein the method comprises a step of: attachinga piston seal to an outer surface of the brake piston such that ananti-rotation feature of the piston seal engages an anti-rotationfeature of the brake piston. 15) The method according to claim 13,wherein the method includes a step of: inserting the brake piston into acaliper bore of a brake caliper. 16) A brake system comprising: a brakepiston comprising a piston pocket, the piston pocket comprises athreaded portion; a spindle comprising a threaded portion, the threadedportion of the spindle is adapted to directly threadably engage thethreaded portion of the piston pocket; one or more ball bearingsprovided in grooves defined by the threaded portion of the of the pistonpocket and the threaded portion of the spindle. 17) The brake systemaccording to claim 16, wherein the brake system comprises a motor,wherein the motor is in communication with the spindle and configured torotate the spindle, and wherein rotation of the spindle causers thebrake piston to move axially. 18) The brake system according to claim17, wherein the brake system comprises a brake pad, and the brake pistonis configured to directly contact the brake pad. 19) The brake systemaccording to claim 16, wherein the brake system comprises a brake pad,and the brake piston is configured to directly contact the brake pad.20) The brake system according to claim 17, wherein the brake systemcomprises a piston seal surrounding the outer surface of the brakepiston, the piston seal comprises a generally annular structure thatcomprises an anti-rotation feature, the anti-rotation feature of thepiston seal is adapted to engage the anti-rotation feature of the brakepiston to restrict or prevent the brake piston from rotating.